Here's a place where I can post my thoughts on new papers, provide updates on my projects, and post info that will eventually be on my website The Theropod Database - http://theropoddatabase.com/ . It will center on theropods, but may delve into other topics as well such as phylogenetics.

Sunday, December 31, 2017

Happy New Years and sorry for the hiatus

So 2018 is upon us, and this blog and the Database have been bereft of updates since Summer. What gives? Well, I've finally been doing what so many of you have urged me to all these years- working on publishable papers. Because of this, there won't be the annual Database update today of all new described taxa. Those entries take a lot of time and I successfully fought the urge to write them. They will be done eventually of course. Similarly, I've wanted to write some blog entries such as one on my acquisition of an original copy of Wild's (1973) Tanystropheus monograph, but that will have to wait.

The good news is that both publishable projects are near completion and could very well be submitted in January. For the Lori project, I just have to check several characters for the maniraptoran OTUs and run the final analysis, then send it to Hartman. These were characters that I refined or quantified, and a few that replaced bad characters. Every taxon that can be usefully resolved is in there, even Halszkaraptor and Almas (which was already included as IGM 100/1323, that I studied at the AMNH). The former doesn't resolve as a basal deinonychosaur and the latter doesn't group with IGM 100/1128, contrary to the only published results for either. Btw, if anyone can write macros for TNT or get me in contact with J. Salvador Arias of the Universidad Nacional de Tucumán, it'd be greatly appreciated.

For the Ornithoscelida project, my team (Cau, Gardner, Deccechi and Marjanovic) and I basically have to provide references for some scores (which I'm responsible for as I did the scoring, and so am the one causing the holdup), complete the bibliography and finish the conclusions. And create figures. I was briefly disheartened by the publication of Langer et al. (2017), but our paper is so much more extensive and explicit that I feel it will significantly add to the conversation, and Langer et al. messed up quite a bit too. For instance, remember how Baron et al. (2017) scored 30 taxa that lack preserved integument as lacking filaments? Langer et al. only changed nine of those scores to unknown despite perhaps being the most obvious error in the matrix. We detail some of their errors in the paper as well.

Me too - but for different reasons, no doubt. I'm especially curious, because of the potential link between the 'swim stroke' of Halszkaraptor and the flight stroke of birds/microraptorines. Did the halskaraptorine swim stroke evolve from the flight stroke (as in the swim stroke of modern diving birds), or independently (which the original description implies)? Fascinating, either way.

I'm not convinced Halszkaraptor was semiaquatic. The nares aren't more retracted than e.g. Gallus or Struthio, the latter of which has even more of a platyrostral condition. The premaxillary neurovascular network is not compared to terrestrial maniraptorans. The arm seems too short to be used actively in swimming. Aquatic reptiles have larger III to II manual digit ratios because just about every reptile except for theropods retains that primitive condition. And sure figure 4b has it in the area of wing-propelled swimmers, but only close to one and doesn't show where terrestrial maniraptorans would fall out.

I've wondered about the short forelimbs of Halszkaraptor. This, plus the fact that the hindlimbs are totally unsuited to aquatic locomotion. I'm not convinced it was a swimmer or diver.But I'm still holding out hope that the forelimbs (and neck) were adapted for some kind of motion underwater. But the 'swim stroke' might not have been used for aquatic locomotion (i.e. propulsion). Perhaps the forelimbs of Halszkaraptor were used for a predatory purpose underwater - sweeping prey (like fish) toward the jaws while it stood still in the water. This is what I thought when I first read the paper.Halszkaraptor forelimbs are weird. So something is going on. But like alvarezsaurs (very weird + very short forelimbs), I'm not convinced by the 'conventional' explanation (swimming for halszkaraptorines, digging for alvarezsaurs).

Halszkaraptor's arms seem most notable to me for being reduced compared to the ancestral maniraptoran/paravian. Reduced structures often have more variable anatomy since they're under less adaptive selection, so you'll get things like a long digit III, shorter penultimate phalanges, etc.. The cervicals suggest emphasis on a strike with the head, as in swans, turtles, drepanosaurs, etc. so maybe this replaced the arms in predation. A possibility is that the large sternum, robust outer digit, posteriorly keeled ulna and bone splints by digit III indicate a well developed wing used in intraspecific combat like some modern birds. Seems more plausible to me than anything involving water.

I'm increasingly attracted to the view that many theropods used their forelimbs not for predation (grasping and holding prey) but for intraspecific combat and/or as a last-resort defense against bigger predators. They (theropod forelimbs) really don't seem to have been much use for catching prey, even in long-armed taxa. Limited anterior reach, and almost no manual prehension.

The snout of Halszkaraptor is way too different from that of Struthio for being comparable. What matters is that it differs from almost all non-neornithine theropods. Only ornithomimosaurs and spinosaurids approach in some elements Halszkaraptor: interesting that both have been suggested to have an aquatic diet.

Two independent morphometric analyses (one on whole set of measurements in 3 dimensions, not just length) both place Halszkaraptor forelimb among aquatic sauropsids.Pending a test of your scenarios, I would appreciate explanation of the results of the morphometric analyses.

Note that we did not suggest a propulsive role for the forearm, but more conservatively stated that forelimb assisted during locomotion in water.

Last, Halszkaraptor finger proportions differ from most reptiles with the third finger longer than the second, and cluster uniquely with long-necked aquatic forms.Again, an alternative explanation of all these results is welcome.

on a totally unrelated note...does anybody know if the dml archives (dml.cmnh.org) are dead? There has been no update there since the 4 January. Also, I've tried to subscribe to the list, but the subscription email bounces always back